全文获取类型
收费全文 | 1553篇 |
免费 | 32篇 |
国内免费 | 1篇 |
专业分类
教育 | 1039篇 |
科学研究 | 129篇 |
各国文化 | 28篇 |
体育 | 193篇 |
文化理论 | 14篇 |
信息传播 | 183篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 32篇 |
2020年 | 51篇 |
2019年 | 71篇 |
2018年 | 104篇 |
2017年 | 78篇 |
2016年 | 86篇 |
2015年 | 41篇 |
2014年 | 58篇 |
2013年 | 316篇 |
2012年 | 51篇 |
2011年 | 54篇 |
2010年 | 39篇 |
2009年 | 48篇 |
2008年 | 42篇 |
2007年 | 36篇 |
2006年 | 33篇 |
2005年 | 22篇 |
2004年 | 18篇 |
2003年 | 25篇 |
2002年 | 21篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 13篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 12篇 |
1993年 | 11篇 |
1992年 | 19篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 5篇 |
1980年 | 12篇 |
1979年 | 14篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1973年 | 3篇 |
1904年 | 3篇 |
1903年 | 3篇 |
排序方式: 共有1586条查询结果,搜索用时 31 毫秒
881.
882.
883.
884.
885.
886.
887.
888.
889.
The aim of this study was to examine the variability of the oxygen uptake (VO2) kinetic response during moderate- and high-intensity treadmill exercise within the same day (at 06:00, 12:00 and 18:00 h) and across days (on five occasions). Nine participants (age 25 +/- 8 years, mass 70.2 +/- 4.7 kg, VO2max 4137 +/- 697 ml x min(-1); mean +/- s) took part in the study. Six of the participants performed replicate 'square-wave' rest-to-exercise transitions of 6 min duration at running speeds calculated to require 80% VO2 at the ventilatory threshold (moderate-intensity exercise) and 50% of the difference between VO2 at the ventilatory threshold and VO2max (50% delta; high-intensity exercise) on 5 different days. Although the amplitudes of the VO2 response were relatively constant (coefficient of variation approximately 6%) from day to day, the time-based parameters were more variable (coefficient of variation approximately 15 to 30%). All nine participants performed replicate square-waves for each time of day. There was no diurnal effect on the time-based parameters of VO2 kinetics during either moderate- or high-intensity exercise. However, for high-intensity exercise, the amplitude of the primary component was significantly lower during the 12:00 h trial (2859 +/- 142 ml x min(-1) vs 2955 +/- 135 ml x min(-1) at 06:00 h and 2937 +/- 137 ml x min(-1) at 18:00 h; P < 0.05), but this effect was eliminated when expressed relative to body mass. The results of this study indicate that the amplitudes of the VO2 kinetic responses to moderate- and high-intensity treadmill exercise are similar within and across test days. The time-based parameters, however, are more variable from day to day and multiple transitions are, therefore, recommended to increase confidence in the data. 相似文献
890.
Colin Williams Pieter Kok Hwang Lee Jonathan P. Dowling 《Informatik - Forschung und Entwicklung》2006,70(3):73-82
Quantum information theory holds the promise of revolutionizing technologies other than computing
and communications. In this article we show how quantum entanglement can be harnessed to beat the Rayleigh
diffraction limit of conventional optical lithography, and to permit nano-devices to be fabricated at a scale
arbitrarily shorter than the wavelength used. Given the relative ease of performing optical lithography
compared with other schemes, and the relative costs associated in migrating the lithography industry to
each new fabrication technology, exploiting quantum entanglement to extend the useful life of optical lithography
could be economically attractive. 相似文献